The present invention is directed to a device for the wavelength-related stabilization of an optical filter, particularly a wavelength-division multiplexer/demultiplexer.
Wavelength-division multiplex/demultiplex methods, wherein different information are transmitted simultaneously by the same fiber on frequency channels defined by different optical carrier frequencies, are being increasingly utilized for the transmission and distribution of information via optical fibers, for example glass fibers. Narrow-band optical filters are required for the multiplexing and demultiplexing of these optical channels.
It must be assured in the optical network that the frequency-related or, respectively, wavelength-related position of the channels of these filters is also constant at various nodes, for example, the filters must be absolutely stabilized to specific wavelengths.
It must be assured in an optical network that the position of the channels of these filters is also constant at various nodes, for example, the filters must be absolutely stabilized for specific wavelengths.
This stabilization can already be assured in the manufacture of filters, for example, see copending U.S. Application Ser. No. 08/765,074, (now U.S. Pat. No. 5,732,171) which is the National Phase for PCT Application PCT/DE95/00745 claiming priority from German Application P 44 22 651.9 and the PCT Application was published on Jan. 11, 1996 as WO96/00915. However, in this filter, the transmission curves can shift relative to one another during operation of the filters at various locations, for example due to different ambient temperatures. This will lead to undesirable additional losses.
A temperature-stabilization of the filters and/or the employment of a reference wavelength have already been proposed for solving this problem. The reference wavelength can be utilized as either being centrally distributed or locally distributed. The central distribution is rather unfavorable, since the optical channel thereby employed is not available for useful signal transmission or is only available therefor to a limited extent.